The present disclosure relates to subject matter contained in Japanese Patent Application No. 10248033 (filed on Sep. 2, 1998), which is expressly incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a wire loop type instrument that is removably inserted into an instrument-inserting channel of an endoscope to carry out excision or the like. The present invention also relates to a method of producing the wire loop type instrument.
2. Description of the Prior Art
FIG. 7 shows a distal end portion of a conventional high-frequency snare for use with an endoscope. In a flexible sheath 1, a control wire 2 is axially movably inserted, and a wire loop 3 formed from an elastic wire is connected to the distal end of the control wire 2 through a connecting pipe 4.
Consequently, the wire loop 3 projects from or withdraws into the distal end of the flexible sheath 1 in response to an operation of advancing or retracting the control wire 2 in the axial direction. When projecting from the distal end of the flexible sheath 1, the wire loop 3 expands in a loop shape by its own elasticity. When pulled into the distal end of the flexible sheath 1, the wire loop 3 is folded.
In the conventional endoscopic high-frequency snare having the above-described structure, however, the inner diameter d of the flexible sheath 1 must be so large that the connecting pipe 4, which connects together the wire loop 3 and the control wire 2, can smoothly move back and forth in the flexible sheath 1.
Accordingly, the flexible sheath 1 becomes thick, and because of the large inner diameter of the flexible sheath 1, when the wire loop 3 is pulled into the flexible sheath 1 to excise a polyp, the polyp pinched tight with the wire loop 3 may be undesirably drawn into the flexible sheath 1, together with the wire loop 3. This may hinder the polyp excision treatment. There are also cases where the polyp cannot be removed from the wire loop 3. In addition, because the outer diameter of the flexible sheath 1 becomes large, the range of applications of the high-frequency snare is unfavorably limited. That is, it is usable only in endoscopes having an instrument-inserting channel with a sufficiently large diameter.